Maybe it wasn’t such a crazy idea after all: A lot more people than you’d think really are watching news at 4:30 in the morning.

Nielsen figures for September show local news viewership from 4:30 to 5 a.m. weekdays nearly tripled since last year, when the only player in the game was NBC-owned WMAQ-Channel 5. Since early August, its four main competitors have added their own newscasts at 4:30 a.m., turning it into a five-way race.

The result has been an overall rise from 42,000 households watching Channel 5 in September 2009 to a total of 119,000 households watching all five local newscasts airing at 4:30 a.m.

As in markets across the country that recently moved up the start of their morning news to 4:30, the strategy is designed to increase viewership for the hours that follow. By that measure, the only winner in Chicago was ABC-owned WLS-Channel 7, which experienced a 4 percent increase in overall ratings from 5 to 6 a.m. Ratings for three others — Channel 5, CBS-owned WBBM-Channel 2, and Tribune Co.-owned WGN-Channel 9 — were unchanged. Fox-owned WFLD-Channel 32 declined 17 percent for the 5 a.m. hour. Terence “T Dog” Henderson, the Chicago media blogger who first predicted the spread of local morning newscasts last April, wrote:

“The reasons why stations are expanding their dawn news shows are simple: more and more viewers are waking up earlier since commute times are longer; advertiser demand; and of course, revenue accrued from the shows… . Morning news is a profitable revenue generator —  stations keep all ad inventory and spots are in high demand for advertisers catching viewers as they head for the door going to work.”

Here’s how viewership from 4:30 to 5 a.m. breaks down by station (with one rating point representing 35,026 households and share representing percent of sets in use):

• Among overall households from 4:30 to 5 a.m., Channel 7 leads with a 1.4 rating and 11 share. Tied for second with a 0.8/6 are Channel 5 and WGN-Channel 9. Tied for fourth with a 0.2/2 share are Channel 2 and Channel 32. (One rating point represents 35,026 households, and share represents percent of sets in use.)
• Among viewers between the ages of 25 and 54, Channel 7 also leads during the half-hour with a 0.6 rating and 9 share, followed by Channel 5’s 0.4/5, Channel 9’s 0.3/5, Channel 32’s 0.2/2, and Channel 2’s 0.1/2.